"Welsh supply teachers are fed up with delays, prevarication, inquiries and reports," said a spokesman.

CASE STUDY

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Media captionAngela Sandles said some supply teachers look at different ways of making ends meet

Angela Sandles, a former nurse, from Monmouthshire, qualified as a primary school teacher in 1999 and worked in Blaenau Gwent for 12 years. She has been a supply teacher for the last six years, so she could also spend time as a foster parent.

"It's far different from classroom teaching. Some experiences can be fantastic, everything is laid out for you. But you can get a call late in the day, you might not have any work left for you, you have to think on your feet. It's not for the faint hearted but it's enjoyable because we only do this job because we care passionately about education."

She said most supply teachers in Wales were now employed via agencies rather than directly by local authorities. After deductions she said she could be paid around the minimum wage.

Ms Sandles described the situation as "diabolical" and said some supply teachers were turning to pizza delivery to make ends meet.

"Supply teachers are voting with their feet and leaving and looking for alternative employment," she said.

"There are lack of opportunities to be paid properly, get proper continuous professional development and a broad spectrum of experience in schools. Newly qualified teachers are being signed up to agencies and guaranteed work. But once they work for an agency they find it hard to gain the broad range of experience schools are looking for.

"I'm coming up to retirement shortly but I'm fighting for younger teachers who need to be looked after.

"Wales should look to Northern Ireland where supply teachers are on a central register, and get them to be paid, if not initially to scale, but at least the £135 [a day] minimum that the agency is charging to a school. Give us that money. We can fill out our own own self-assessment form and do tax and national insurance."